Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
  • C08G18/72—Polyisocyanates or polyisothiocyanates
  • C08G18/77—Polyisocyanates or polyisothiocyanates having heteroatoms in addition to the isocyanate or isothiocyanate nitrogen and oxygen or sulfur
  • C08G18/78—Nitrogen
  • C08G18/79—Nitrogen characterised by the polyisocyanates used, these having groups formed by oligomerisation of isocyanates or isothiocyanates
  • C08G18/798—Nitrogen characterised by the polyisocyanates used, these having groups formed by oligomerisation of isocyanates or isothiocyanates containing urethdione groups
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C265/00—Derivatives of isocyanic acid
  • C07C265/12—Derivatives of isocyanic acid having isocyanate groups bound to carbon atoms of six-membered aromatic rings
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
  • C08G18/40—High-molecular-weight compounds
  • C08G18/60—Polyamides or polyester-amides
  • C08G18/603—Polyamides
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
  • C08G18/703—Isocyanates or isothiocyanates transformed in a latent form by physical means
  • C08G18/705—Dispersions of isocyanates or isothiocyanates in a liquid medium
  • C08G18/707—Dispersions of isocyanates or isothiocyanates in a liquid medium the liquid medium being a compound containing active hydrogen not comprising water

Definitions

• the present invention related to a process for the preparation of stable dispersions of finely divided polyisocyanates in a liquid by treating polyisocyanates with stabilizers, wherein the polyisocyanates dispersed in the liquid and treated with the stabilizer are finely dispersed and/or milled under the action of high shear forces, and the preparation of heat-crosslinkable isocyanate systems.
• polyisocyanates Because of their good reactivity, polyisocyanates have become very important for many applications, for example for adhesives, sealants and decorative and protective coatings on many hard and flexible substrates, and for the production of particle boards and compact and foamed synthetic materials.
• the reactants are stored as separate formulations and only mixed directly before application, after which the reaction takes place spontaneously or is accelerated by heat and/or a catalyst.
• polyisocyanates are first reacted with a monofunctional reactant.
• the adducts obtained are referred to as blocked isocyanates if they are less thermally stable than the products of the crosslinking reaction subsequently to be carried out. On exposure to heat, the blocking agent is eliminated and the polyisocyanate forms the more thermally stable bond, with crosslinking.
• the concept underlying these patents comprises dispersing polyisocyanates, in particular solid polyisocyanates, in media capable of reacting with isocyanates, to give a product which is stable during storage, premature undesirable reaction of the isocyanate groups with the surrounding medium being prevented by virtue of the fact that the disperse isocyanates are deactivated at their surface or, as stated in German Laid-Open Application No. DOS 3,230,757, possess retarded reactivity.
• the basic concept is the same in each case.
• This deactivation or retardation is achieved if the surfaces of the isocyanate particles-are treated with less than the stoichiometric amount, based on the total content of isocyanate, of a deactivating agent.
• deactivating agents particularly suitable substances being those which react with isocyanates to give urea or polyureas.
• the purpose of using the stated deactivating polyisocyanates, which form stable dispersions in media capable of reacting with the isocyanate groups is to provide single-component isocyanate systems, i.e. after elimination of the deactivation, the isocyanates are intended to react with the reactive substances in which they are dispersed and thus to form the desired end products, e.g. coatings, adhesive bonds or materials.
• the deactivating or retarding reactions are preferably carried out in situ, i.e. in the media which are suitable for producing the desired end products and capable of reacting with isocyanates.
• the isocyanate and the medium capable of reacting with the isocyanate are used in suitable ratios of equivalents. This is always readily feasible if these media, for example polyhydroxy compounds or sluggishly reacting, sterically hindered amines, react with the isocyanates more slowly than do the rapidly reacting amine compounds, which have been suggested as preferred stabilizers.
• the stabilized isocyanate is generally isolated by filtration, if necessary carefully dried, and mixed in the isolated, finely powdered form with the desired (polyol) starting materials for the single-component polyurethane reactive mixtures.
• these deactivated polyisocyanates are used, as described in the stated patents, to obtain chemically stable dispersions directly in media capable of reacting with isocyanates or indirectly after isolation of the deactivated polyisocyanates.
• the present invention describes routes to such advantageous dispersions, which are chemically and physically stable dispersions of polyisocyanates in low-viscosity media.
• the present invention relates to a process for the preparation of stable dispersions of finely divided polyisocyanates in a liquid which may or may not contain surfactants, protective colloids and other assistants, by treating a polyisocyanate with one or more stabilizers in the presence or absence of the liquid, wherein the polyisocyanate dispersed in the liquid and treated with stabilizers is finely dispersed or milled under the action of high sheaf forces, if necessary with the addition of further stabilizer.
• Particularly advantageously used polyisocyanates are those which are solid at room temperature.
• Suitable liquids are both liquid substances which are inert to isocyanate groups and liquid substances capable of reacting with isocyanate groups, or a mixture of the two types of substances. Water or an aqueous solvent mixture may also be used as the liquid.
• Preferred stabilizers are polyamidoamines.
• the present invention furthermore relates to a process for the preparation of heat-crosslinkable isocyanate systems, wherein the stable dispersions of finely divided polyisocyanates, which dispersions are prepared by the novel process, are used as crosslinking agents.
• Polyisocyanate dispersions which are chemically and physically stable at room temperature and storage temperatures up to about 60° C. can be obtained according to the invention, the polyisocyanate being dispersed, in the form of discrete particles which are deactivated on their surface, in media which are reactive and/or inert toward isocyanates.
• the dispersions are preferably subjected, in the presence of wetting agents and/or protective colloids, to a subsequent milling or subsequent dispersing procedure which controls the particle size.
• Stabilization of the polyisocyanates is carried out according to the invention in general by applying a type of polymer shell.
• This polymer shell is formed from the isocyanate groups attached to the surface of the polyisocyanate particles and one or more compounds capable of reacting with isocyanate groups, only a minor amount, i.e. from 0.01 to 30, preferably from 0.1 to 5% of the total amount of isocyanate groups present being consumed.
• stabilizers the compounds which form the polymer shell and are capable of reacting with isocyanates are referred to as stabilizers.
• the polymer shell may be formed in situ, i.e. in the dispersion itself, or externally, i.e. in a liquid medium which may be the same as or may differ from, that subsequently used in the dispersion, or directly, for example by applying the stabilizer to solid, finely powdered polyisocyanates in a suitable mixer.
• deactivated polyisocyanates provided with the polymer shell and exhibiting a retarded reactivity may also be referred to as stabilized polyisocyanates.
• the stabilized polyisocyanate should be present in the dispersion in as high a concentration as possible.
• the medium in which the stabilized polyisocyanate is dispersed is a liquid. This may be a low-viscosity liquid incapable of reacting with isocyanates, and/or a low-viscosity liquid capable of reacting with isocyanates.
• the stabilized polyisocyanate should be dispersed in amounts such that it is present substantially in excess of the stoichiometric amount, since, according to the invention, it is intended to make available substances which externally appear isocyanate-free and can be used for a variety of applications in the same way as free isocyanates, without having the disadvantages and dangers associated with handling of free isocyanates, for example health hazards and only a short shelf life (pot life) of the ready-to-use formulations.
• the dispersions are finely dispersed and/or milled under the action of high shear forces; these steps may be carried out in particular in the presence of surfactants and/or viscosity regulators and/or other assistants, and correspond to a subsequent dispersing step or subsequent milling step which controls the particle size.
• This after-treatment makes it possible to provide physically and chemically stable dispersions, i.e. dispersions which, even when stored for a long time, maintain their content of free isocyanate at a constant level and form no sediment or only loose sediment which can easily be stirred up again.
• a surprising aspect, and one not suggested by the prior art, is the possibility of carrying out this after treatment with high-power dispersing apparatuses, e.g. stirred ball mills or dissolvers, even in media capable of reacting with isocyanates, e.g. water or water-containing mixtures, without the isocyanates reacting with these media to more than only a slight extent.
• high-power dispersing apparatuses e.g. stirred ball mills or dissolvers
• the liquid serving as the dispersing medium may contain surfactants, protective colloids and other assistants, e.g. catalysts.
• Suitable polyisocyanates for the novel process are all di- or polyisocyanates or any mixtures of these, provided that they have a melting point above 10° C., preferably above 40° C., particularly preferably above 80° C.
• These may be aliphatic, cycloaliphatic, araliphatic or, preferably, aromatic and heterocyclic polyisocyanates, or polyphenyl-polymethylene-polyisocyanates, obtained by aniline/formaldehyde condensation followed by phosgenation, according to British Pat. Nos.
• arylpolyisocyanates as well as perchlorinated arylpolyisocyanates, carbodi- imide-containing polyisocyanates, allophanate-containing polyisocyanates, isocyanurate-containing polyisocyanates, urethane-containing or urea-containing polyisocyanates, polyisocyanates containing acylated urea groups, biuret containing polyisocyanates, polyisocyanates prepared by telomerization reactions, ester-containing polyisocyanates, and preferably uretdione-containing diisocyanates and urea containing diisocyanates.
• suitable polyisocyanates of this type are:
• 1,5-naphthalene diisocyanate, 3,3'-diisocyanato-4,4'-dimethyl-N,N'-diphenylurea, dimeric 1-methyl-2,4-diisocyanatobenzene, dimeric 4,4'-diisocyanatodiphenylmethane and 3,3'-dimethyl-4,4'-diisocyanatodiphenyl are particularly preferably used.
• Suitable stabilizers for these polyisocyanates are the substances stated in German Laid-Open Applications Nos. DOS 3,112,054, DOS 3,228,670, DOS 3,228,723 and DOS 3,230,757. These are compounds which produce a sort of polymer shell on the surface of the polyisocyanate particles.
• Preferably used stabilizers are those which form this polymer shell by reacting selectively with the isocyanate groups on the surface of the particles. As a result of this reactive stabilization, the polymer shell is bonded firmly to the polyisocyanate particles without substantial proportions of the total amount of isocyanate groups present being consumed.
• the isocyanate consumption is in general from 0.01 to 30, preferably from 0.01 to 10, particularly preferably from 0.01 to 5%.
• useful stabilizers are compounds possessing hydroxyl, carboxyl, phenolic hydroxyl, amide or mercaptan groups.
• Reactions which lead to urea or polyurea structures on the isocyanates are also particularly useful for deactivating the isocyanate groups on the surface of the polyisocyanate particles, i.e. for stabilizing the isocyanate dispersions, because the said structures are insoluble in most polyols and organic solvents.
• Urea forming or polyurea-forming reagents of this type are water and primary or secondary amines.
• Suitable amine stabilizers for the stated polyisocyanates are bifunctional or polyfunctional, low molecular weight or high molecular weight compounds possessing aliphatically bonded, primary and/or secondary amino groups and/or terminal --CO-NH-NH 2 groups and/or hydrazines and having a molecular weight of from 32 to about 60000, preferably from 60 to 3000.
• These are, for example, low molecular weight and/or high molecular weight primary and/or secondary polyamines, preferably diamines.
• the amino groups are in general bonded to aliphatic groups, cycloaliphatic groups or the aliphatic radical of araliphatic groups.
• Hydrazine (generally in the form of hydrazine hydrate) or alkyl-substituted hydrazines, such as N,N'-dimethylhydrazine, may also be used.
• Other suitable amine stabilizers are compounds possessing terminal hydrazine groups, e.g. dihydrazides, such as oxalic dihydrazide, adipic dihydrazide or terephthalic dihydrazide, and compounds possessing hydrazide and semicarbazide, carbazate or amino groups, e.g.
• ⁇ -semicarbazidoalanyl hydrazide 2-semicarbazidoethylene carbazate, aminoacetic hydrazide, ⁇ -aminopropionic hydrazide or ethylene-bis-carbazate or ethylene-bis-semicarbazide.
• Polyhydrazides which are obtained by hydrazinolysis of polyacrylates and whose preparation is described, for example, by M. Hartmann, R. Dowbenko and U.T. Hockswender in Organic Coating +Applied Polymer Science 46 (1982), 429-432 are also very useful.
• aliphatic or cycloaliphatic diand polyamines which, in addition to the amino groups, may furthermore possess OH, tertiary amino, ether, thioether, urethane or urea groups are preferred.
• di- and polyamines which can be used according to the invention are ethylenediamine, 1,2- and 1,3-propanediamine, 1,4-butanediamine, 1,6-hexanediamine, neopentanediamine, 2,2,4- and 2,4,4-trimethyl-1,6-diaminohexane, 2,5-dimethyl2,5-diaminohexane, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, bis-aminomethyl-hexahydro4,7-methano-indane (TCD-diamine), 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, 1-amino-3,3,5-trimethyl
• DOS 1,193,671 by aminating polypropyleneglycolsulfonic acid esters (U.S. Pat. No. 3,236,895), by treating a polyoxyalkylene glycol with epichlorohydrin and a primary amine (French Pat. No. 1,466,708) or by reacting NCO prepolymers with hydroxyl-containing enamines, aldimines or ketimines and hydrolyzing the product, as described in German Laid-Open Application No. DOS 2,546,536.
• Other suitable higher molecular weight di- and polyamines are the polyamines which are accessible by the methods described in German Laid-Open Applications No.
• DOS 2,948,419 and DOS 3,039,600 via the carbamate stage, by alkaline hydrolysis of NCO prepolymers with bases.
• Other very useful higher molecular weight polyamines are the substances which are prepared by polycondensation of polycarboxylic acids, e.g. polymeric linseed oil fatty acid, with an excess of diamines and triamines and are available, for example, as Versamide® from Schering AG. These higher molecular weight polyamines have molecular weights of about 400-6000, preferably 400-3000. Because of their composition, such higher molecular weight polyamines are particularly useful for producing a non-brittle, resilient polyurea shell.
• any combinations of the stated amine, hydrazine and hydrazide stabilizers may be used in order, for example, to balance disadvantageous side effects of one amine by corresponding advantages of other amines (for example, low molecular weight and high molecular weight diamines used in combination) or in order to combine as many advantageous side effects as possible.
• suitable combinations are combinations of rapidly reacting amines, e.g. ethylenediamine, with amines slowed down by steric hindrance, or combinations of low molecular amines or hydrazines with high molecular weight amines, e.g. aliphatic aminopolyethers.
• catalysts may also be added. Preferred catalysts are those which selectively accelerate the deactivation. However, the deactivation catalysts may be identical to the catalysts which subsequently accelerate or control the intended heat-activated reaction.
• the liquid i.e. the dispersing liquid medium
• the liquid may be reactive and/or inert toward isocyanate groups. Since it is the object of the present invention to provide isocyanate crosslinking agents for a large number of applications, the novel stable dispersions should have a very high content of available isocyanate. It is therefore advantageous if the selected dispersing media which are reactive toward isocyanate groups possess a very high equivalent weight.
• suitable liquid media are low-molecular weight and/or high molecular weight mono- and/or polyols and/or aromatic polyamines, preferably those having molecular weights from 60 to 6000.
• Other examples are fairly long-chain alcohols, such as isohexyldecanol, and propoxylation products of monohydric alcohols having molecular weights of, preferably, from 400 to 6000, e.g. propoxylation products of n-butanol.
• suitable low molecular weight polyols are ethylene glycol, N-methyldiethanolamine, castor oil, polyethylene glycol ethers having a molecular weight of from 400 to 6000, ethoxylation or propoxylation products of low molecular weight di- and polyols having molecular weights of from 400 to 6000, propoxylated trimethylolpropane, propoxylated ethylenediamine, linear or branched polypropylene glycol ethers which may contain proportionate amounts of ethylene oxide randomly distributed, arranged in blocks or present as terminal groups and have molecular weights of from 400 to 6000.
• Propoxylation products of ethylenediamine e.g. a tetraalcohol of ethylenediamine and propylene oxide, are also suitable.
• liquid compounds which are usually employed for the preparation of polyurethane plastics and are reactive toward isocyanates.
• examples of these are polyethers, polythioethers, polyacetals, polycarbonates, polylactones, polyesteramides or polyesters possessing two or more hydroxyl groups, as well as polybutadiene compounds.
• Polyethers and polyesters are particularly preferred.
• Suitable polyethers are those of the conventional type, which may be prepared, for example, by polymerization of tetrahydrofuran or of epoxides such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide or epichlorohydrin, or by means of an addition reaction of these epoxide compounds, preferably ethylene oxide or propylene oxide, with water, diamines and low molecular weight diols and triols.
• epoxides such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide or epichlorohydrin
• Polyesters which are obtained by condensation of polyols with polycarboxylic acids, polycarboxylic anhydrides or polycarboxylic esters are also suitable. Polyesters obtained from lactones, e.g. ⁇ -caprolactone, or hydroxycarboxylic acids, e.g. ⁇ -hydroxycaproic acid, can also be employed.
• Polyacetals for example the compounds which can be prepared from glycols and formaldehyde, are also useful.
• Suitable hydroxyl-containing polycarbonates are those of the conventional type, for example those which can be prepared by reacting propane-1,3-diol, butane-1,4-diol and/or hexane-1,6-diol, di-, tri- or tetraethylene glycol or thiodiglycol with a diaryl carbonate, e.g. diphenyl carbonate, or phosgene.
• a diaryl carbonate e.g. diphenyl carbonate, or phosgene.
• Liquid polybutadienes containing terminal hydroxyl groups are also suitable according to the invention, as are copolymers of olefinically unsaturated monomers without active hydrogen atoms, and olefinically unsaturated monomers possessing active hydrogen.
• Polyhydroxy compounds modified with vinyl polymers and as obtained, for example, by polymerization of styrene and acrylonitrile in the presence of polyethers or polycarbonate-polyols, are also useful liquids for the novel process.
• Plasticizer-type compounds e.g. phthalates, such as dioctyl, diisododecyl, dibenzyl or butyl benzylphthalate, or phosphates such as trioctyl phosphate, may also be used as the liquid medium for stabilizing the polyisocyanates.
• Hydrocarbons such as butadiene oils, or polyethers having a fairly high molecular weight can also be employed as the reaction medium.
• extenders and/or solvents which are not capable of reacting with isocyanates also makes it possible to regulate the equivalent weight of the dispersions. It is also possible to use only the stated solvents and/or water.
• Some of the substances which can be used as the liquid medium also have a stabilizing effect. In such cases, it is possible to dispense with a further stabilizer. This is the case, for example, with some dispersions in water or water/solvent mixtures. In such cases, the stabilizing reaction ceases after the polymer shell has formed.
• the surfactants preferably used in the after-treatment to control particle size are conventional anionic, cationic or neutral surfactants, e.g. sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, arylsulfonates, alkali metal salts of higher fatty acids, oxyethylated oleylamine, sulfosuccinates, soyabean lecithin, polyethylene oxide fatty acid esters, polypropylene oxide fatty acid esters and decynediol derivatives.
• Condensates of phenolsulfonic acids, urea and formaldehyde, as described in German Pat. Nos. 1,113,457 and 2,327,579, are particularly useful.
• assistants which may or may not be useful, are antiskinning agents, antifoams and especially viscosity regulators, such as cellulose esters, methylcellulose, ethylcellulose, polymeric acids and salts of polymeric acids, natural and synthetic polysaccharides and prttein products, after-treated starch, polyureas, for example as described in German Laid-Open Applications Nos. DOS 2,359,929 and DOS 2,360,019, and polyarylamides, polyvinyl alcohols, polyvinyl ethers, etc.
• viscosity regulators such as cellulose esters, methylcellulose, ethylcellulose, polymeric acids and salts of polymeric acids, natural and synthetic polysaccharides and prttein products, after-treated starch, polyureas, for example as described in German Laid-Open Applications Nos. DOS 2,359,929 and DOS 2,360,019, and polyarylamides, polyvinyl alcohols, polyvinyl
• Heating the novel dispersions of finely divided polyisocyanates eliminates their retardation or deactivation.
• novel dispersions can therefore very advantageously be employed for formulating heat-crosslinkable isocyanate systems, suitable reactants being the conventional ones, such as polyetherpolyols, polyesterpolyols, hydroxyl-containing polymers and other substances which are reactive toward isocyanate groups, in the presence or absence of low molecular weight chain extenders possessing hydroxyl and/or amino groups.
• the temperature required for the crosslinking reaction depends on the reactivity of the reactants and on any catalysts present. It is in general from 70° to 180° C., preferably from 90° to 150° C.
• Suitable units for producing high shear forces for the novel fine dispersing or milling procedure are those known from milling and dispersing technology, e.g. stirred ball mills, bead mills, sand mills, ball mills, slot mills, high-speed dissolvers or dispersing apparatuses of the rotor/stator type.
• novel dispersing or milling procedure in the presence of substances which are reactive toward isocyanate is advantageously carried out at temperatures below the reaction temperature of the particular mixture of substances used, preferably at from 0° to 60° C., in particular from 10° to 40° C.
• 500 parts of a polyetherpolyol based on glycerol and propylene oxide and having a molecular weight of about 4000 are initially taken in a cooled planetary mixer.
• This dispersion is after-treated in a high-speed disperser of the rotor/stator type (Ultra-Turrax) to give a homogeneous low-viscosity dispersion which, after a few days, forms a little loose sediment which can easily be stirred up.
• the chemical stability is defined by checking the free isocyanate content. (The analytical method does not detect the isocyanate groups blocked in the uretdione bond.)
• the dispersion from Example 2a is mixed with 800 parts of 1% strength solution of the ammonium salt of a copolymer of 60 parts of styrene, 10 parts of acrylic acid and 30 parts of maleic anhydride, using a high-speed disk stirrer.
• the result is a dispersion which shows a pronounced tendency to settle out and forms very compact sediment which is difficult to stir up.
• Example 2c The dispersion from Example 2b is further milled in a cooled open stirred ball mill at 20°-26° C. for 15 minutes. The result is a chemically and physically stable dispersion which, even after prolonged standing, forms only loose sediment which can easily be stirred up.
• Example 3a 2500 parts of the dispersion described in Example 3a are added, and the mixture is then further dispersed by milling for 20 minutes in a cooled open stirred ball mill. This further dispersing greatly reduces the mean particle size and gives a narrower particle size distribution (cf. Figure). The subsequent milling does not significantly reduce the isocyanate content of the dispersion. In determining the isocyanate content, the blank value due to the assistants should be taken into account.
• the dispersion forms a little loose sediment which can very easily be stirred up, and the isocyanate content remains stable.

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• 1985
  • 1985-05-14 DE DE19853517333 patent/DE3517333A1/de not_active Withdrawn
• 1986
  • 1986-05-09 DE DE8686106318T patent/DE3676559D1/de not_active Expired - Lifetime
  • 1986-05-09 AT AT86106318T patent/ATE59380T1/de not_active IP Right Cessation
  • 1986-05-09 EP EP86106318A patent/EP0204970B1/de not_active Expired - Lifetime
  • 1986-05-12 JP JP61106914A patent/JPS61261314A/ja active Pending
• 1987
  • 1987-10-23 US US07/112,049 patent/US4888124A/en not_active Expired - Lifetime

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